The name of the host and the game, the map name, how many players are in the game, and the ping of the server (connection speed).
If you want to join a game, click the name of the game twice. When you are in the game, you are on team GDI or NOD. They all have different units (see vehicles and infantery in the main menu). There are many sorts of infantry. Infantry who can shoot, and infantry for repair. At the purchase terminals you can uprgrade your character, or buy new vehicles. There are two sorts of vehicles two, transport vehicles, and tanks and stuff.
Each side (GDI and NOD) has his own base camp. The base has often 5 buildings. A defend structure, a structure for vehicles, one for infantry, a power plant (if this is destroyed costs off all units= x2, and the defense structure doesn't work), and a tiberium refinery(money). The refinery has a harvester to collect money. If a base is destroyed, the game is over. You can destroy a base by destroying all buildings, or put a beacon on the beacon padestal (this does only work if this function is set ON by the host).